Significance With the acceleration of industrialization, air pollution is increasingly severe. The global outbreak of COVID-19 in 2019, along with the widespread transmission of diseases such as influenza A, influenza B, and mycoplasma pneumonia in recent years, has greatly impacted public health and safety. Developing industrial filters capable of filtering air pollution particles and personal protective materials isolating viruses is crucial. Electrospinning technology prepares air filtration nanofiber materials with unique nanofiber structures and high specific surface areas, enabling efficient capture and removal of fine particles and viruses with high filtration efficiency. Additionally, these materials possess excellent durability and stability, maintaining efficient filtration performance over prolonged use and can be widely applied in air purification filters and personal protective masks.
Progress Different scales of nanofibers can be obtained through melt-electrospinning, solution electrospinning, and airflow-assisted electrospinning. Melt-electrospinning melts the polymer by heating and then draws it into filaments through a high-voltage electrostatic field. The production speed is high, but it is only suitable for a small part of the polymer raw materials, and the fibers are thicker. Solution electrospinning dissolves polymer materials in organic solvents to form a polymer solution. Under the action of a high-voltage electrostatic field, the polymer molecules in the solution are stretched into fibers, and nanofibers with very small fineness can be prepared. However, the subsequent processing of organic solvents may cause environmental pollution and the output is small. Airflow-assisted electrospinning is based on electrospinning and injects airflow into the fiber formation area to assist stretching and control fiber formation. This method can control fiber diameter and shape, but the equipment is complex, process control is difficult, and the cost is high. Adding nanoscale particles to the spinning solution can roughen fiber surface, significantly increasing the material's specific surface area, filtration efficiency, and reducing filtration resistance. Constructing nanofiber structures resembling spider webs, dendrites, grooves, or bead chains can achieve similar effects. Adding functional ingredients or particles to the solution can confer properties such as high-temperature resistance, antibacterial, and antiviral effects on the material. To scale up nanofiber production, research on electrospinning mechanisms has been conducted, validating models with experimental results, significantly improving production yield through enhancing new needleless spinning devices.
Conclusion and Prospect Currently, the regenerative and reusable capabilities of electrospun air filtration nanofiber materials are limited, potentially leading to higher long-term operational costs. Materials often have low mechanical strength, making them susceptible to physical damage. Scaling up electrospinning production still faces challenges. Hence, there is a necessity for deeper investigations into electrospinning mechanisms, delving into the impact mechanisms and structure-property correlations involving electric fields, solutions, and fiber formation. For melt-electrospinning, it is necessary to control the interference of heating equipment on the high-voltage electric field to further improve the production speed and product stability. Solution electrospinning requires the development of environmentally friendly degradable materials or recyclable solvents on the basis of increasing yields to achieve environmentally friendly production. Airflow-assisted electrospinning requires optimized processes and equipment, reduced costs, and enhanced airflow control of fiber morphology to expand the range of applications. Moreover, achieving precise control over fiber morphology and material structure formation is imperative. It is crucial to develop novel technologies that enable efficient and stable large-scale production. Simultaneously, developing nanofiber materials with self-cleaning, antibacterial, and sensing functionalities to enhance their application value in the air filtration field is crucial. Combining novel nanofiber materials with fiber functional modification techniques can further expand the application fields of electrospun nanofiber materials. With continuous technological innovation and deeper research, the potential of electrospun nanofiber materials in the air filtration field will be more fully realized and applied.
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